1. Field of the Invention
The invention relates to a touch sensing device and a touch sensing apparatus using the touch sensing device, and particularly, the invention relates to a touch sensing device proceeding touch sensing through electrowetting effect and a touch sensing apparatus using the touch sensing device.
2. Description of the Prior Art
Touch panel originated from the idea of electric touch sensing interface brought up by Dr. Samuel Hurst in the year 1971, and then the first touch panel appeared in the year 1974. Touch panel was firstly developed by the American army for military purposes, and after the technology was transferred to the non-governmental circles, it was developed for various applications.
Nowadays, because of the high development of wireless network and electronic industry, portable electronic devices with wireless communication and small size, such as, Personal Digital Assistant (PDA) or mobile phone, are used in various occasions to meet the demands of the market. The small size touch panel which has both the advantages of simple operation and small volume gradually replaces traditional input devices, such as keyboard, mouse, trackballs, and so on, because of the portability and functions.
Touch panels could be divided into resistive, capacitive, optical, and ultrasonic touch panels. The resistive touch panel is formed by two Indium Tin Oxides (ITO) conductive layers with one above the other. When an object touches one of the ITO conductive layers to make it deform to contact the other of the ITO conductive layers, the panel forms a voltage variation which could be sensed by a controller, so as to calculate the position of the contact point for input.
The capacitive touch panel generates induced current to sense the position of the contact point according to the capacity variation generated by static electricity combination of transparent electrodes arranged in order and the object contacting the panel.
The principle of the optical touch panel is assigning infrared ray senders and receivers to make the infrared ray in the panel arranged in matrix of X axis and Y axis. The opaque object would interdict the infrared ray at the contact point when it contacts the panel, and the position of the contact point could be decided according to the coordinates of the interdicted infrared ray.
The surface of the ultrasonic touch panel is made of glass, and the ultrasonic wave senders configured at the corner of the panel form a uniform sound wave field at the center area of the panel. When a soft object contacts the panel, the ultrasonic wave would be absorbed and then the intensity thereof decreases. According to the decay of the intensity of the received signal, the controller can calculate the position of the contact point.
Following the development of the touch sensing technique, the portable electronic device could be provided with more functions and the operation thereof could be more convenient and direct. For example, multiple touch sensing make the touch panel execute more complex input orders, and the user can easily make these orders without memorizing more input method. On the other hand, the touch panel could also be used for measuring the contacting force and pressure.
However, to achieve the above-mentioned functions of the portable electronic device, the design of the circuits and the electrodes of the touch panel would be complex, therefore, the transparency thereof is easily influenced and then the intensity of the light emitted from the display panel under the touch panel is also decreased by the touch panel. As seen above, the illumination of the image displayed by portable electronic device would be insufficient and hurts the sight of the user. On the other hand, the manufacturer may increase the intensity of the light emitted from the display panel for the image illumination, and then it causes power consumption of the portable electronic device.